#include <stdio.h>

void swap(int & a,int & b){
   printf("%d %d\n",a,b);
   int t;
   t = a;
   a = b;
   b = t;
}

int main(){
	int a = 5;
	int b = 7;
	swap(a,b);
   printf("%d %d\n",a,b);
   return 0;
}

